1. Technical Field
The present invention is directed toward window operators, and more particularly toward window operators for controlling movement of a window sash relative to the window frame.
2. Background Art
There are, of course, any number of different types of window (and other closure) operators which are well known in the art. Examples of such operators are shown, for example, in Van Klompenburg U.S. Pat. No. 4,136,578, Van Klompenburg et al. U.S. Pat. No. 4,241,541, Peterson et al. U.S. Pat. No. 4,253,276, Erdman et al. U.S. Pat. No. 4,266,371, Nelson U.S. Pat. No. 4,305,228, Sandberg U.S. Pat. No. 4,346,372, Vetter U.S. Pat. No. 4,497,135, Tacheny et al. U.S. Pat. No. 4,521,993, Vetter U.S. Pat. No. 4,617,758, Allen U.S. Pat. No. 4,823,508, Tucker U.S. Pat. No. 4,840,075, Nolte et al. U.S. Pat. No. 4,843,703, Nolte et al. U.S. Pat. No. 4,845,830, Tucker U.S. Pat. No. 4,894,902, Tucker et al. U.S. Pat. No. 4,937,976, Nolte et al. U.S. Pat. No. 4,938,086, Berner et al. U.S. Pat. No. 4,945,678, Tucker et al. U.S. Pat. No. 5,054,239, Tucker et al. U.S. Pat. No. 5,152,103, and Vetter et al. U.S. Pat. No. 5,199,216.
Generally speaking, such operators have used a variety of linkages in combination with suitable hinge structures, where the operator linkages are actuated by rotation of a manual or powered drive connected to the linkage through assorted gear drives. The linkage used in one type of operator, known as a dual arm operator (as shown, for example, in Van Klompenburg et al. U.S. Pat. No. 4,241,541), includes two arms selectively pivotable relative to each other about a common axis with the other ends of the arms suitably linked to a window sash whereby such relative pivoting causes the sash to move as desired.
Unfortunately, the gear drives typically used with window operators require that there be some clearance or backlash between the gear teeth so that the different gears can fit together without interference or binding. As a result, such operators allow the connected sash a significant amount of unrestricted and undesirable free travel. The amount of such free travel can be reduced (though not entirely eliminated) by using gears manufactured with low tolerances, but the cost of such gears typically increases as the tolerances are lowered.
The need for high quality (and therefore generally high cost) gears in prior art operators is further enhanced by the high loads typically incurred by such window operators. Such loads arise, for example, when breaking the weatherstrip seal during initial opening of the sash and when closing the window sash to seal about the entire periphery of the weather strip. As a result, it is has been necessary to use high strength materials such as suitably hardened metals in the drive train of the operator. Also, given the characteristics of such high strength materials, it has typically been necessary to protect the materials from corrosion, with such corrosion protection being difficult to ensure given the long expected useful life of such operators, particularly where the operators are used in corrosive environments such as found in seaside dwellings.
Notwithstanding the above strength and durability requirements, it is also desirable to minimize the size of the operator in order to minimize as much as possible the intrusion of the operator into the open viewing area provided through the pane opening of the sash. Conventionally, manual window operators have handles which can be manually pivoted, which such handles extending into the room and, to varying degrees, the window viewing area. Not only do such handles affect the aesthetics of the window, but they also are susceptible to damage and/or can themselves cause damage if, for example, accidentally bumped. Further, such susceptibility to bumping can also create a risk that the operator might be accidentally and unknowingly moved to an undesirable position where, for example, forced entry might be easier, or where a tight weather seal is not provided. In order to minimize such risks, folding handles have been used in some installations, where the handle when not in use can be folded to a position in which its extension into the room (and thus its susceptibility to accidental bumping) is reduced. Such structures can, however, adversely impact the ease of manual operation of the operator when used to change the window position.
Prior art operators have to varying degrees been unable to address all of the above design constraints in a suitable manner.
The present invention is directed toward overcoming one or more of the problems set forth above.